1. Field of the Invention
This invention relates generally to tube-launched missiles and particularly to a method of upgrading a missile to incorporate advances in technology.
2. Description of Related Art
Advancements in technology force a missile to be upgraded. These advancements can be in the warheads, guidance systems, materials, or even fundamental design changes. When it is possible, these advancements are incorporated into the missile in such a way that the basic missile doesn't become antiquated or obsolete.
To facilitate the incorporation of technological advancements, many missiles have become modular in nature. This means, for example, that the propulsion unit is practically a stand-alone unit having a standardized interface with other modules of the missile such as the electronics module, the warhead module, etc.
Modularity requires that the interfaces between the modules be "standardized" so that an upgraded module does not necessitate changes in other modules.
For a tube-launched missile, this requirement for "standardization" applies not just to the missile itself, but also to the launcher/case. The launcher or missile case contains the missile prior to launch and not only provides information to the tube-launched missile but also provides an initial electrical current flow.
Often the incorporation of a technological advancement changes the electrical current demands of the missile. Although missiles are originally designed with an excess margin of current, in some applications, the current requirements of a particular advancement will exceed this margin. In this situation, short of redesigning the entire case/launcher and missile, it is impossible to incorporate the technological advancement. In such a case, the particular upgrade cannot be incorporated into the missile and the missile stands to become obsolete.
It is also known that electrical current for start-up of a missile in pre-launch is needed primarily to start the components that will be used to guide and propel the missile in flight. Start-up is accomplished by firing squibs to activate such devices as the gyros or to initiate the operation of the flight batteries.
As example, assume that a tube-launched missile has a ten amperes capacity. Also assume that the squibs for two batteries and a gyro system, each requiring two amperes, must be fired prior to flight, giving a total requirement of six ampreres. The excess margin is therefore only four amperes. Should a technological advancement to the missile require five amperes to operate or begin operation, it could not be incorporated without alterations to the launcher/case or other missile components. In addition, even if current requirements fall within the margin of four amperes, no margin would be left for error and the entire missile system could easily fail.